Snooker is played on a rectangular snooker table with six pockets, one at each corner and one in the middle of each long side. The table usually has a slate base, covered in green baize. At one end of the table (the baulk end) is the baulk line, which is 29 inches (74 cm) from the baulk cushion (the short cushion at the baulk end). A semicircle of radius 111⁄2 inches (29 cm), called the D, is drawn behind this line, centred on the middle of the line. The cushion at the other end of the table is known as the top cushion.
A regulation (full-size) table is 12 ft × 6 ft (3.7 m × 1.8 m); because of the large size of these tables, smaller tables are common in homes, pubs and other places where space is limited. These are often around 6 feet (1.8 m) in length, and all the dimensions and markings are scaled down accordingly. The balls used are sometimes also scaled down, and/or reduced in number (in the case of the reds) such that the longest row of balls in the rack is omitted.
Snooker balls, like the balls for all cue sports, are typically made of phenolic resin, but are smaller than pool balls. Regulation snooker balls (which are specified in metric units) are nominally 52.5 mm (approximately 2 1⁄15 inches) in diameter, though many sets are actually manufactured at 52.4 mm (about 2 1⁄16 in.) Some recreational sets (which are usually not measured metrically) are 2 1⁄8 in. (about 54 mm) up to as large as pool balls, at 2 1⁄4 in. (about 57.2 mm); larger ball size requires wider pocket openings. Miniature sets also exist, for half-size home tables. There are fifteen red balls, six “colour” balls (yellow, green, brown, blue, pink, and black), and one white cue ball. Usually none of the balls are numbered, though the six colour balls often are in the US, where they are easily mistaken at first glance for pool balls (the design is similar, but the numbering does not match pool’s scheme).
At the beginning of a frame, the balls are set up in the arrangement shown in the illustration. The six colours (a term referring to all balls except the white and the reds) are placed on their own spots. On the baulk line, looking up the table from the baulk end, the green ball is located where the “D” meets the line on the left, the brown ball in the middle of the line, and the yellow ball where the “D” meets the line on the right. This order is often remembered using the mnemonic God Bless You, the first letter of each word being the first letter of the three colours. At the exact centre of the table sits the blue ball. Further up the table is the pink ball, which sits midway between the blue spot and the top cushion, followed by the red balls, arranged in a tightly-packed triangle behind the pink (the apex must be as close as possible to the pink ball without touching it). Finally, the black ball is placed on a spot 32.5 cm (12.8 in) from the top cushion.
The objective of the game of snooker is to strike the white cue ball with a cue in the direction of other object balls and to pot these object balls in one of the six pockets. This must be done according to the rules of the game, described below. By potting object balls points can be scored. The player who scores most points wins the frame, and the player who wins most frames wins the match.
A match usually consists of a fixed, odd number of frames. A frame begins with setting up the balls as described above. A frame ends when all balls are potted, or when one of the players concedes defeat because he is too far behind in score to equal or beat the score of the other player.
A match ends when one of the players has won the majority of the set number of frames and the other player can therefore not equal this. For example, when a match consists of 19 frames, the match ends when one of the players has reached 10 frames.
At the beginning of each frame the balls are set up by the referee as explained. This will be followed by a break-off shot, on which the players take turns. At the break-off, the white cue ball can be placed anywhere inside the D, although it is common for players to start by placing the ball on the line, between the brown ball and either the green or yellow ball.
Players take turns in visiting the table. When one player is at the table, the other cannot play. A break is the number of points scored by a player in one single visit to the table. A player’s turn and break end when he fails to pot a ball, when he does something against the rules of the game, which is called a foul, or when a frame has ended.
The ball or balls that can be hit first by the white are called the ball(s) “on” for that particular stroke. The ball(s) “on” differ from shot to shot: a red ball, if potted, must be followed by a colour, and so on until a break ends; if a red is not potted, any red ball remains the ball “on”. Only a ball or balls “on” may be potted legally by a player. If a ball not “on” is potted, this is a foul.
If the cue ball is touching another ball which is on or could be on, the referee shall state that the ball is a “touching ball”, whereupon the striker must “play away” from the ball without moving it, and—because the touching ball is deemed to be the object ball—without being required to hit another ball. If the object ball moves, a foul shall be called (see “Push shot”). No penalty is incurred for thus playing away if (1) the ball is on; (2) the ball could be on and the striker nominates such ball; or (3) the ball could be on and the striker nominates, and first hits, another ball that could be on. If the cue ball is touching another ball which could not be on, it isn’t called a touching ball, and the striker must play away from it and hit a legally nominated object ball. Where the cue ball is touching several object balls simultaneously, the referee shall state “Touching ball” for each and every object ball he deems the cue ball to be touching and indicate to the player which object ball he is referring to. Either player may request the referee to confirm which object balls have been deemed a “touching ball” and the rules for each individual “touching ball” event apply simultaneously.
If a ball is potted when a foul is made, depending on the situation, the potted ball will either stay off the table, or be spotted on its initial spot or it will—along with any and all balls that were moved during the foul shot—be repositioned to where it/they lay before the shot. For details on such situations, see Fouls and Miss below.
The game of snooker generally consists of two phases. The first phase is the situation in which there are still red balls on the table. In the first phase, at the beginning of a player’s turn, the balls “on” are all remaining red balls. The player must therefore attempt to first hit and pot one or more red balls. For every red ball potted, the player will receive 1 point. When a red has been potted, it will stay off the table and the player can continue the break. If no red has been potted or a foul has been made, the other player will come into play.
In case one or more red balls have been potted, the player can continue the break. This time one of the six colours (yellow, green, brown, blue, pink and black) is the ball “on”. Only one of these can be the ball “on” and the rules of the game state that a player must nominate the desired colour to the referee, although it is usually clear which ball the striker is playing and it is not necessary to nominate.
When the nominated colour is potted, the player will be awarded the correct number of points (yellow, 2; green, 3; brown, 4; blue, 5; pink, 6; black, 7). The colour is then taken out of the pocket by the referee and placed on its original spot. If that spot is covered by another ball, the ball is placed on the highest available spot. If there is no available spot, it is placed as close to its own spot as possible in a direct line between that spot and the top cushion, without touching another ball. If there is no room this side of the spot, it will be placed as close to the spot as possible in a straight line towards the bottom cushion, without touching another ball.
Because only one of the colours is the ball “on”, it is a foul to first hit multiple colours at the same time, or pot more than one colour (unless a free ball has been awarded, see below).
If a player fails to pot a ball “on”, it being a red or nominated colour, the other player will come into play and the balls “on” are always the reds, as long as there are still reds on the table.
The alternation between red balls and colours ends when all reds have been potted and a colour is potted after the last red, or a failed attempt to do so is made. All six colours have then to be potted in ascending order of their points value (yellow, green, brown, blue, pink, black). Each becomes the ball “on” in that order. During this phase, when potted, the colours stay down and are not replaced on the table, unless a foul is made when potting the colour, in which case the colour is respotted.
When the colours have been potted, the frame is over and the player who has scored most points has won it (but see below for end-of-frame scenarios).
A foul is a shot or action by the striker which is against the rules of the game.
When a foul is made during a shot, the player’s turn is ended and he will receive no points for the foul shot. The other player will receive penalty points.
Common fouls are:
- failing to hit any other ball with the cue ball
- first hitting a ball “not-on” with the cue ball
- potting a ball “not-on”
- potting the white (in-off)
- hitting a ball other than the white with the cue
- making a ball land off the table
- touching the cue ball with something other than the tip of the cue (except while positioning the cue ball “in-hand”; while “in-hand” the cue ball may be touched by anything except the tip of the cue)
- playing a “push shot” – a shot where the cue, cue ball and object ball are in simultaneous contact
- playing a “jump shot”, which is where the cue ball leaves the bed of the table and jumps over a ball (even if touching it in the process) before first hitting another ball
- playing a shot with both feet off the ground
Should a cue ball be touched with the tip while “in-hand”, i.e. when breaking-off or playing from the “D” after being potted, a foul is not committed as long as the referee is satisfied that the player was only positioning the ball, and not playing, or preparing to play, a shot.
When a foul is made, the other player will receive penalty points. Penalty points are at least 4 points and at most 7 points. The number of penalty points is the value of the ball “on”, or any of the “foul” balls, whichever is highest. When more than one foul is made, the penalty is not the added total — only the most highly valued foul is counted.
Not hitting the ball “on” first is the most common foul. Players can make life difficult for an opponent by making sure that they cannot hit a ball “on” directly. This is most commonly called “snookering” one’s opponent or alternatively “laying a snooker” or putting the other player “in a snooker”.
Because players receive points for fouls by their opponents, snookering one’s opponent a number of times in a row is a possible way of winning a frame when potting all the balls on the table would be insufficient to ensure a win.
If a player commits a foul, and the opponent considers that the position left is unattractive, he may request that the offender play again from the resulting position.
If a foul has been committed by not hitting a ball “on” first, or at all, and the referee judges that the player has not made the best possible effort to hit a ball “on”, and neither of the players are in need of snookers to win the frame, or would be after the penalty points were applied, then “foul, and a miss” is called. In this instance the other player may request that all balls on the table are returned to their position before the foul, and the opponent play the shot again. (In top class play, this will usually require only the cue ball and a couple of other balls to be moved.) This rule is often applied less stringently, if at all, in amateur matches.
Since jump shots are explicitly forbidden, it can happen that the ball “on” is physically impossible to hit even with a swerve shot. (This can happen, for instance, if the cue ball is crowded into a corner and closely surrounded by several reds after a red was potted. It is technically possible to drive one’s opponent into a physically impossible snooker by dislodging several colours in one shot, but this is virtually unheard of.) In this case the player is nevertheless required to nominate a ball and attempt to hit it, i.e. to play in the direction that would hit it if the obstacles were not present. A foul shot will inevitably be called, but since the task was impossible, this will never be a miss, and the game continues normally.
A free ball occurs after a foul shot where the resultant layout of the table leaves the opponent “snookered”. The opponent of the player who committed the foul can choose any other ball on the table as a replacement for the ball in question, and pot this as if it were the intended ball. For example, if the ball “on” is a red, and the free ball is a pink, the player will receive one point for potting the pink (which is then respotted). He then continues to attempt to pot a colour which, if successful, is followed by another red etc. If a colour was ball on, and both the nominated ball and the actual ball on are potted, only the ball on is scored. The free ball is spotted while, as this can only occur in the final stage of the frame, the ball on will stay off the table. This is the only time while attempting to pot a colour that two balls can be pocketed without a foul occurring. If the ball on is red and both the nominated and ball on are potted, then each ball potted is scored as a red, as would be typical if it were not a free ball. The colour free ball is then spotted and the ball on remains off the table.
It is allowed to play a snooker using the free ball, providing the snooker does not leave all balls ‘on’ snookered behind the ball which has just been used as the ball ‘on’. It is allowed to cannon a ball nominated as a red into another red, so as to pot this (a plant).
The only exception to this rule is if the “on” ball is a red that is being obstructed by another red. For example, if the player breaking-off hits the white too soft and it does not hit the triangle of reds, a free-ball would not be called, even though no red can be hit on both sides, since the only thing preventing some of the reds being hit on both sides is another red.
A free ball scenario does not occur when the ball gets stuck at the edge of a pocket jaw (commonly referred to as “angled’) in such a manner that the player is unable to hit any legitimate ball. This is because according to the official snooker rules a ball is snookered only if its way is obstructed by balls not on. In this scenario, after a foul, the player may choose to either take the shot from the current position or ask the offender to play again.
After a free ball, a coloured ball will be played if red balls are still on the table; if not, the player will continue with the lowest value ball.
A miss will be called if a player does not hit the ball “on” first and is deemed by the referee to have not made a good enough attempt at the shot. This gives the opponent the option of having the balls replaced as they were and have the fouling player take the shot again. A miss would not normally be called should the offending player require snookers, but there are exceptions. Firstly, it may be possible to make full central contact with a ball “on” with a plain straight stroke, in which case a miss would be called every time an unsuccessful attempt at hitting it was produced. Secondly, it is still up to the referee’s discretion whether an adequate attempt at hitting the object ball was made. If the referee deems that the snookered player has made no genuine effort to hit the ball, a miss can still be called despite snookers being required.
The rule was introduced to prevent players from playing professional fouls (i.e., deliberately fouling so as to leave the balls in a safe position, reducing the risk of giving a frame-winning chance to the opponent). Multiple misses often occur because players attempt to hit a shot very softly or thinly in situations where a fuller contact might leave their opponent an easy potting chance. This can lead to an apparently easy escape being attempted several times, as players feel that it is better to concede many points but leave a safe position, than concede none and leave a frame-winning chance.
However, the applied interpretation of the rule has proved controversial, as players sometimes narrowly miss a shot many times. Sometimes this is due to bad luck, or the difficulty of a snooker, meaning that a good snooker can pay more dividends than a great pot.
A frame normally ends in one of three ways:
- A concession, when one player gives up due to being too far behind to have a realistic chance of winning the frame. Concession before the snookers-required stage may be interpreted as ungentlemanly conduct and result in a penalty of a second frame being applied.
- When the pink is potted in the final stage of the frame, and the potting player leads by more than seven points as a result. The striker may pot the black, for example to complete a high-scoring break, if he so desires.
- The final black is potted legally (including after a respot), and the seven points scored puts one player ahead.
There are three less common ways to end a frame:
- A foul on the black, when the black is the only ball left. It is sometimes wrongly assumed that play continues after a foul on the black if there are fewer than seven points between the scores. This is not the case: the player who is in the lead following the assessment of a penalty after a foul when only the black remains is the winner.
- Failure to hit a ball “on” three times in a row, if the player has a clear sight of the ball. The referee will warn a player after a second such miss that a third miss will mean that the opponent will be awarded the frame. This rule does not apply if the player is snookered. As missing due to avoiding a direct shot on a ball is usually a tactical, rather than skill-related, outcome, this rule is rarely invoked, as a player will simply hit the ball directly on the third shot.
- If the referee deems a player is taking too long to take the shot, the player may be warned. If the player continues to hesitate, the frame may be awarded to the other player at the discretion of the referee. In practice, a delay of over two minutes can result in such a forfeiture.
If the score is tied after the final black is potted, the black is “respotted” and the cue ball put “in hand”. The referee will then toss a coin, with the player winning the toss choosing who will take first strike at the black. Play then continues normally until the black is potted or another frame-ending situation occurs.
The highest break that can be made under normal circumstances is 147. To achieve that, the player must pot all 15 reds, with the black after every red, followed by potting the six remaining colours. This “maximum break” of 147 rarely occurs in match play.
If an opponent fouls before any balls are potted, and leaves the player a free ball, the player can then nominate a colour and play it as a red ball. Then, black can be nominated as the next colour. This means it is actually possible to score the value of 16 reds and blacks (16 * 8), plus the values of all the colours (27), which equals 155 points scored.
The highest possible score, as distinct from the highest possible break, is unlimited and depends on the value of points scored from the opponent’s foul shots when added to the player’s own scored points (which may not require the highest break).